In earlier times, relay control system was dominant in industrial control fields. Generally, the relay control system operates sequentially according to a predetermined time or condition. If the control sequence needs to be changed, the wiring of the relay control system has to be changed accordingly, which is inconvenient and inflexible.
In the 1960s, computer technology came into use in the industrial control field. However, due to its high cost, complexity in programming, and difficulty to work in the harsh industrial environment, computer technology is not widely applied in the industrial control field.
With the growth of needs in industrial control fields, control apparatuses come into being. The control apparatus is a master device which controls an electromotor to start, regulate speed, brake and reverse by changing wirings and resistance of a main circuit or a control circuit according to a predetermined sequence. Control apparatuses cooperate with other apparatus, such as sensors and actuators, to be applied in various industrial equipments.
Typically, industrial equipments are used in complex applications with various requirements. Many applications require that a control apparatus can operate normally powered by a backup power supply when losing its main power supply. However, the backup power supply generally has a low power, just like batteries, which can not sustain the control apparatus to work for a long time with high power consumption. Therefore, it is important to provide a power module with a low power consumption design for the control apparatus.
With the growth of technology, there are more and more strict requirements for low power consumption design for a power supply of an industry apparatus. To address this issue, switching to a backup power supply once a power-off of the main power supply is monitored is provided in later solutions. However, the power consumption of the backup power supply is not reduced with the later solutions.
Improvements have been made to the later solutions in the existing technology, in which circuits of the control apparatus are divided into two parts: one part which stops working once the main power supply is cut off, and the other part which still needs to work normally powered by a backup power supply. Compared with the later solution, power consumption of the backup power supply is reduced, but not to the least.
U.S. Pat. No. 7,382,062B2 provides a stabilized wide voltage range power supply for actuators, which realizes to convert a single power input into three power supplies. However, this disclosure fails to disclose low power consumption design for the power supply.
Chinese patent application No. 200610025600.9 provides a method and device to realize dual processing system for an actuator control system, which divides the control system into a master processing system and a processing system with mini power consumption. If an external power supply (namely, main power supply) is cut off, the master processing system stops working, while the processing system with mini power consumption is powered by an interior power supply (namely, backup power supply), which reduces power consumption of the interior power supply. However, in case that the interior power supply has a low power or is a battery, power consumption of the power supply as disclosed is still very high and needs to be further reduced.